1. Field of the Invention
This present application relates to a mobile terminal and corresponding method for determining a proper charging current according to a charging capacity of a dedicated charger.
2. Background of the Invention
A mobile terminal can perform various functions such as video and voice call communications, capturing still or moving images using a camera, recording voice data, reproducing music files through a speaker system, displaying image or video, playing games, viewing video or TV broadcast programs, etc. Thus, the mobile terminal functions as a multimedia player. Mobile terminals also may include a touch function and graphical user interface (GUI) allowing the user to easily input information into the mobile terminal. The mobile terminal can also be charged using a variety of chargers. For example, the user can use a travel adaptor (TA) to charge their mobile terminal with a current of 700 mA or 800 mA through a USB cable. However, the related art charger is often not sufficient to meet the user's demands.
For example, many users now have smart phones, which combine many traditional personal computer features with calling features. However, the smart phone requires more battery capacity. An amount of time needed to charge the phone is also often too long. More concretely, when a battery having a charging capacity less than 1000 mA is used, a TA of 700 mA is used (substantially, 600 mA). On the other hand, when a battery having a charging capacity more than 1000 mA is used, a TA of 1 A is used (substantially, 800 mA or 900 mA).
Manufacturers are also developing the TA of 1 A to reduce a charging time. In this instance, the TA of 700 mA needs to be distinguished from the TA of 1 A. The only method for distinguishing the TA of 700 mA from the TA of 1 A is to check an ID resistance of a USB cable which connects the TA to the mobile terminal. This method is used to determine the TA type having a predetermined capacity and includes checking an inner resistance of a USB plug coupled to a receptacle of the mobile terminal when the TA is connected to the mobile terminal through the USB cable.
For example, when the inner resistance of the USB plug is 180KΩ, the method determines that the TA of 700 mA is connected to the mobile terminal. On the other hand, when the inner resistance of the USB plug is 220KΩ, the method determines that the TA of 1 A is connected to the mobile terminal. A charging operation is then performed for charging the mobile terminal with a current set according to the determined TA type.
Many problems occur in the related art when charging the mobile terminal, because there is no effective method for detecting the charging capacity of the TA. For example, one problem occurs when the mobile terminal is charged using a USB type TA of a small capacity. In this instance, the TA overloads causing explosions. For instance, when a smart phone preset to be charged using the TA of 1 A is to be charged using TA of 700 mA, the mobile terminal tends to supply a charging capacity of 1 A to a battery. As a result, an overload occurs on the TA. Further, the TA is often damaged when an over current protection is applied to the TA.
In addition, when connecting the TA of 700 mA to the mobile terminal through a USB cable of 220KΩ, a controller of the mobile terminal determines that the TA of 1 A is currently connected to the mobile terminal. Then, the controller sets a charging current as 800 mA to perform a charging operation. The mobile terminal also tends to supply a charging capacity of 800 mA to a battery. As a result, an overload can occur on the TA, and thus the TA may be damaged.